diff --git a/Makefile b/Makefile
index b2a9586..315ffa5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-TEST_REQUIREMENTS=nose coverage
+TEST_REQUIREMENTS=nose coverage mock
 
 all: install
 install:
diff --git a/bluepyopt/ephys/simulators.py b/bluepyopt/ephys/simulators.py
index 6c0e7b7..6853f69 100644
--- a/bluepyopt/ephys/simulators.py
+++ b/bluepyopt/ephys/simulators.py
@@ -110,8 +110,6 @@ def run(
         if cvode_active is None:
             cvode_active = self.cvode_active
 
-        self.neuron.h.cvode_active(1 if cvode_active else 0)
-
         if not cvode_active and dt is None:  # use dt of simulator
             if self.neuron.h.dt != self.dt:
                 raise Exception(
@@ -122,6 +120,8 @@ def run(
                     'init dt: %.6g' % (self.neuron.h.dt, self.dt))
             dt = self.dt
 
+        self.neuron.h.cvode_active(1 if cvode_active else 0)
+
         if cvode_active:
             logger.debug('Running Neuron simulator %.6g ms, with cvode', tstop)
         else:
diff --git a/bluepyopt/tests/test_ephys/test_simulators.py b/bluepyopt/tests/test_ephys/test_simulators.py
index 4e78de5..a2cd984 100644
--- a/bluepyopt/tests/test_ephys/test_simulators.py
+++ b/bluepyopt/tests/test_ephys/test_simulators.py
@@ -25,6 +25,8 @@
 import nose.tools as nt
 from nose.plugins.attrib import attr
 
+import mock
+
 import bluepyopt.ephys as ephys
 
 
@@ -37,12 +39,29 @@ def test_nrnsimulator_init():
 
 
 @attr('unit')
+def test_nrnsimulator_init_windows():
+    """ephys.simulators: test if NrnSimulator constructor works on Windows"""
+
+    with mock.patch('platform.system', mock.MagicMock(return_value="Windows")):
+        neuron_sim = ephys.simulators.NrnSimulator()
+        nt.assert_is_instance(neuron_sim, ephys.simulators.NrnSimulator)
+        nt.assert_false(neuron_sim.disable_banner)
+        nt.assert_false(neuron_sim.banner_disabled)
+
+        neuron_sim.neuron.h.celsius = 34
+
+        nt.assert_false(neuron_sim.disable_banner)
+        nt.assert_false(neuron_sim.banner_disabled)
+
+
+@attr('unit')
 def test_nrnsimulator_cvode_minstep():
     """ephys.simulators: test if NrnSimulator constructor works"""
 
     # Check with minstep specified
     neuron_sim = ephys.simulators.NrnSimulator()
     nt.assert_equal(neuron_sim.cvode.minstep(), 0.0)
+    nt.assert_equal(neuron_sim.cvode_minstep, 0.0)
 
     # Check with minstep specified, before after simulation
     neuron_sim = ephys.simulators.NrnSimulator(cvode_minstep=0.01)
@@ -64,3 +83,35 @@ def test_neuron_import():
     from bluepyopt import ephys  # NOQA
     neuron_sim = ephys.simulators.NrnSimulator()
     nt.assert_is_instance(neuron_sim.neuron, types.ModuleType)
+
+
+@attr('unit')
+def test_nrnsim_run_dt_exception():
+    """ephys.simulators: test if run return exception when dt was changed"""
+
+    from bluepyopt import ephys  # NOQA
+    neuron_sim = ephys.simulators.NrnSimulator()
+    neuron_sim.neuron.h.dt = 1.0
+    nt.assert_raises(Exception, neuron_sim.run, 10, cvode_active=False)
+
+
+@attr('unit')
+def test_nrnsim_run_cvodeactive_dt_exception():
+    """ephys.simulators: test if run return exception cvode and dt both used"""
+
+    from bluepyopt import ephys  # NOQA
+    neuron_sim = ephys.simulators.NrnSimulator()
+    neuron_sim.neuron.h.dt = 1.0
+    nt.assert_raises(ValueError, neuron_sim.run, 10, dt=0.1, cvode_active=True)
+
+
+@attr('unit')
+@mock.patch('glob.glob')
+def test_disable_banner_exception(mock_glob):
+    """ephys.simulators: test if disable_banner raises exception"""
+    mock_glob.return_value = []
+
+    nt.assert_raises(
+        Exception,
+        ephys.simulators.NrnSimulator.  # pylint: disable=W0212
+        _nrn_disable_banner)